Most users use the GIS Tools plug-in or the MWGeoProc library to merge shapes.
This is not always working, due to the version of NTS library that is being used.

Both the plug-in and the library are scheduled to be rewritten using GEOS methods.

This script is showing how to do that in the mean time:
MergeShapes.cs

Open the shapefile you want to work with. Select the shapes you want to merge using the selection tool or a query in the attribute table editor.
Run the script.
A new shapefile has been made in the same folder as the original shapefile. No attributes have been copied.

Hope it helps.

Paul

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Paul Meems
The Netherlands
[www.bontepaarden.nl]
Release manager, configuration manager and
forum moderator of MapWindow GIS

Owner of MapWindow.nl - Support for
Dutch speaking users: www.mapwindow.nl

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